The present invention relates to an electro-mechanical plug release indicator system for use in well cementing operations.
In well cementing operations ensuring the positive release of the cementing plug is a serious problem. It is critical to the cementing operation for the operator to know when the plug releases so that the volume of cement being pumped downhole can be measured.
Typical prior art cementing plug containers utilize a mechanical lever actuated type plug release indicator to indicate the passage of the cementing plug from the cementing plug containers. In some instances, these prior art mechanical lever actuated type plug release indicators may indicate the passage of the cementing plug from the cementing plug container, although the cementing plug is still contained within the container. The failure to properly release the cementing plug from the cementing plug container can ruin an otherwise profitable well cementing job due to the over-displacement of the cement to insure an adequate amount of cement has been pumped into the annulus between the casing and wellbore.
Another type of cementing plug indicator utilizes a radioactive nail placed into the cementing plug in the cementing plug container. When the cementing plug having the radioactive nail lodged therein is no longer present in the cementing plug container, a radiation measuring instrument, such as a Geiger counter, will not react to the radiation emitted from the radioactive nail in the cementing plug thereby indicating that the plug is no longer in the cementing plug container. However, since the shelf life of readily available and easily handled radioactive nails is limited, such nails may be difficult to obtain and store, when working in remote areas.
Additionally, an accoustic type plug release indicator can be utilized in which a microphone detects the sound of the plug moving through the well casing and transmits the signal to an operator listening system and a magnetic tape recorder.